One sweep type bender for thin wall metallic conduit



Oct. 16, 1951 R. H. HENDERSON 2,571,241

ONE SWEEP TYPE BENDER FOR THIN WALL METALLIC CONDUIT Filed Oct. 22, 1949 2 Sheets-Sheet l I N V EN TOR. 17 0,5812 ffidsgyfivierawz Oct. 16, 1951 -R. H. HENDERSON 2,571,241

ONE SWEEP TYPE BENDER FOR THIN WALL METALLIC CONDUIT Filed Oct. 22, 1949 2 Sheets-Sheet 2 Patented Oct. 16, 1951 UNITED STAT ES ICE ONE-SWEEP grin fiitivnanr on grnIN WALL METALLIC CONDUIT Robert Halsey'I-fenderson, East Orange, N. J. Application-October 2'2, lsisalseriaino; its-017 a claims? (01. -8 1-' i This invention relates to an improved hand electrical wiringindustry as electrical metallic tubing; and the invention has reference, more particularly, toa bender tool adapted to be manipulated so as to -produce elb'ow b ends in such' tubing by a single or continuous bending sweep of the tool relative-to the, tubing or 'vice versa, as: distinguished from step by step bending operationsadapted to be -produced by hand benders' of the hickey type. u u

p wall metallic conduit or electrical metallic tubing is used to house electric wiring installations; and must be bent to conform to the desired course-'orrunof the-wiring; The wiring must be drawn through the conduit to extend from outlet to outlet, and consequently bends in the course ofthe conduit should be free from kinks, flattening or other distortion which might interfere with or impede the drawing of the electrical wires therethrough.

Most-bending tools of the one or' continuous sweep type have bee'n designed for use only with thick wall conduit or pipe, the thick walls of which are reliedon resist distortion, but such bending tools-are not satisfactory'for use in bend-l ing thin wall conduit or tubing, the thin walls of which, in the absence of proper support, offer little resistance to distortion during the bending 0per-' ation.

Some attempts have been made to provide a hand bender of the one or continuous sweeptype for use'inbending thin wall metallic conduit or tubing. In such benders, however, the depth of the bending groove approximates the diameter of the conduit or tubing, so that bending stresses are set up. in the conduit'or tubing before it can enter between and gain the lateral support of said walls, with the result that the walls of the conduit or tubing are not braced in resistance to distorting stresses, and consequently flattening of the conduit or tubing occurs, especially at points rearwardly of the fulcrum of bending stress application. Furthermore, in such benders, the form of the abutment, by which the conduit or tubing is anchored subject to application of bend ing stress, is not such as to provide a mai'zimum extent of the conduit or tubing between the abutment and the opposed bending groove end which will facilitate easy working or break down of the conduit or tubing as applied bending stress is initiated, and thereafter to efiect foreshortened gripv on the conduit or tubing as the bending thereof progresses,

tut-home Having tirabtvem-view, it'i's an object of this invention to 1) (Wide a novel construction ofharrd tenderer the oneorcoritmuous sweep typewhichf ise'specially" adapted for pendin min wall meter:- lic' conduit o'i"tiibingfwithout occurrence ofkinks} flattening or like distortion thereof; the never bender birig charac' riz'ed'by an arcuateb'odyi pfovidd wltfia'bendi'ffg groove which is bounded by partner side wens; said Walls being" spaced apartffidis'talfice"substantially corresponding to the dTaIrHetef' dftheofid l'i'or tubingto be bh'tj said walls, attheen'traiice orifin'er end portion of'th bfid'iflg gro'oyl being or a heigl'i'tappibxifffalt'i fig ofifarid dfie fialf' totwic'e' the diameter" of thboiiduit'or'tubirig, suc'hheight" referably: css'arilygdiniifii's'hing toward the-outer I en figfgrooveftd 'a'height, at such outer end, approsmratmg the diameter of the condiiitbi'"tubirig"., Due to such'height of the" side want oT-the tifding'grotve; the' con uit-trtubing is laterally" supported 'S'aid" wans'not onlyat tfi ruicrfim of'appl'ied bending stress but alsoalong aconsiderable portion of theunbent length of tfi b'nd'ifit 'oftubing'which extends" tangentially rearward" from the "fulcrum of appliedberi'ilir'i, sti" A further object of this invention i's'toprovi'd'e a hand,'tnar"tbci'naving' the no'verside-wau bounded tnuffia r'dbve as above stated-,- tool al'so 'ir'i'oluc'fsa never construction and range'iiient'of -conduit ort'ubin'ganchoring ab t)- merit; the latter being "offenses and related to" the' efitraiice or ifirY our the bending groove that'it 'initiallygri the conduit or tubing "in such manner as to effect a long"bite thereupon, whereby to provide a maximum length of the conduit or t bifigin xt fisib'fibtwen thesarii and the rancefid erratum oftlfe banning groove, an 7 thereby to'facilitate easy break down or theta du tbrtuning un'drtne endin -stress mainlyap ueautereto; and the eafter 'tdeflect a shortened bite argnp on'sam c nsumer tub'ifig as t bending thereof proceed'stoa finish. Other" 'obli'ctjsfof' this invention, not at*this tiinefmdrje v particularly enumerated, will b'uifrdfst'o'odffoih 'tl'le 'followi fig'" detailed description or the-same; 7 I

Anfillustrative embodiment of this invention is" shown in"tlie attempt-wing drawin gs in which: d I V formance of the bending operation; Fig. 2 is a top plan view of the bender tool, the conduit or tubing being omitted; and Fig. 3 is a rear end elevation of the bender tool, the conduit or tubing being also omitted in this view.

Fig. 4 is a longitudinal vertical sectional view of the bender tool, showing a length of conduit or tubing undergoing initial phases of the bending operation; and Fig. 5 is a view similar to that of Fig. 4, but showing the conduit or tubing undergoing the final phase of the bending operation.

Similar characters of reference are employed in the above described views, to indicate corresponding parts.

Referring to the drawings, the reference character I indicates the main body of the bender tool which is of generally arcuate shape, the arcuate length of which approximates 90. Said body is provided intermediate its ends, for substantially radial extension therefrom, with a socketed shank l I. Said shank or a suitable part thereof is internally screw-threaded for the reception of the threaded end of a lever arm [2, by which the body may be either held or swung, as the case may be, when in conduit or tubing bending use. The outer periphery of said body defines the bottom l3 of a curved bending groove, the radius of its curvature corresponding to the radius of an elbow bend desired to be produced in conduit or tubing by use of the tool.

Extending along the sides of the body l0 and outwardly from the bottom l3 of the bending groove, so as to form the sides of said groove, are upstanding side walls 14. These side walls l4 are spaced apart at a distance corresponding to the diameter of the conduit or tubing l to be bent; the spacing being a few thousandths of an inch in excess of said diameter, so as to provide suflicient clearance for entrance of the conduit or. tubing therebetween, and yet afford the required lateral support of said conduit or tubing during bending operation of the tool. It will thus be understood that the side walls [4 and bottom l3 complete an endwise open, curved bending groove which extends from end to end of the body l0.

One side wall I 4 projects forwardly beyond the forward end of the body so as to form a carrying arm I6. This carrying arm extends from said side wall in the plane thereof, and provided in connection with the free end of said carrying arm is a transverse abutment or anchoring post l'l. Said abutment or anchoring post is spaced outwardly from the forward end of the bending groove at a distance somewhat in excess of the diameter of the conduit or tubing to be bent, thus providing a laterally open entrance way [8 through which the conduit or tubing may be passed for engagement with the abutment or anchoring post and then disposed in aligned relation to the bending groove.

The inner or forward end of the bending groove provides a shoulder l9 which constitutes an initial bending fulcrum adapted to be engaged by the conduit or tubing [5, when the latter is entered in the tool between the body I0 and said abutment or. anchoring post I! preparatoryto a bending operation. The abutment or anchoring post 11 is grooved or notchedtransversely to its axis to provide a diametrically extending receiving seat 20 to embrace the entered conduit or tubing [5. The plane of said receiving-seat 20 is disposed. acutely angular to the axis of the straight or unbent conduit or tubing 15 as initially entered between said abutment or anchoring post and the initial bending fulcrum forming shoulder IQ of the bending groove, thus providing said abutment or anchoring post with an outer conduit or tubing impingement shoulder 2| and an inner conduit or tubing impingement shoulder 22, for purposes subsequently explained herein when describing the operation of the tool.

The height of the side walls I of the bending groove, beginning at the forward or inner end of said groove, should approximate from one and one-half to twice the diameter of the tubing or conduit to be bent. Such height may be substantially uniform throughout the length of the bending groove, but preferably gradually diminishes toward the rearward or outer end of said groove, being at such rearward or outer end however still of a height which is somewhat in excess of the diameter of the conduit or tubing, at least at that part of the bending groove where the bending of a right angle elbow bend of the conduit or tubing is completed.

In the use of the novel bender tool, the conduit or tubing l5 may be worked against the tool while the latter is held stationary, or the tool may be worked against the conduit or tubing by swinging the tool relative thereto.

As shown in Fig. 1, to initiate the bending operation, the straight unbent conduit or tubing [5 is passed laterally through the entrance way [8, so as to engage the same between the seat 28 of the abutment or anchoring post I1 and the shoulder [9 at the entrance of the bending groove, which shoulder I9 provides the initial fulcrum about which the bending operation is begun. By reference to Fig. 1 of the drawings, it will be noted, when the straight unbent conduit or tubing is thus initially engaged by the tool, that, due to the angular divergence of the receiving seat 20 of the abutment or anchoring post relative to the axis of conduit or tubing, said conduit or tubing engages the outer impingement shoulder 2|, but is offset from the inner impingement shoulder 22. Due to this, the conduit or tubing may be said to be engaged by a long bite, i. e. a maximum length of the conduit or tubing [5 is disposed between the impingement points of the abutment or anchoring post and the initial bending fulcrum shoulder Hi. This is of marked advantage, for it allows greater freedom of reactive movement of the conduit or tubing, as well. as less resistance to molecular readjustment of the metal of the conduit or tubing, at the moment of applied initial bending stress, thereby facilitating bending break down or working of conduit or tubing metal and thus substantially eliminating risk of flattening or kinking of said conduit or tubing where the bend curvature begins. As shown in Fig. 4, when initial bending stress is applied, the length of conduit or tubing intermediate the long bite impingement shoulder 2| and the fulcrum shoulder I9 is free to arch under the bending stress, until such arching brings the conduit or tubing into engagement with the'short bite impingement shoulder 22, so that thereafter, as the bending operation continues, the shorter length of conduit or tubing between said impingement shoulder 22 and fulcrum shoulder l9 not only firmly anchors the conduit or tubing subject to continued bending, but, by reason of the reduced gripped length thereof, a stronger resistanceto distortion is assured.

Again referring to Fig. 1, the disposition of the straight unbent conduit or tubing, as initially amateinounted in the tool= preparatory to the bending operation; is such that; due to the great height" of the side walls l4 of the bendinggroove; a-

very substantial-length ofthe' conduit or tubing,

which extends tangentially rear-ward from the initial fulcrumof appliedbending-stress provided byshoulder I9, isembraced'and. laterally sup-- This is ported by and between said sidewalls. also a very important factor with respect to adequate control of the conduit or tubing against flattening or other distortion, since likelihood of distortion is at, a maximum, in that part of the conduit or tubing which extends immediately behind the fulcrum: of applied bending. stress, which part is moving toward but has not-yet:b.ecome seateddnthe;bending groove was to be stopped by the bottom is of the latter. It will be obvious, that in tools whereinthe side walls ofjthebending groove are-ofa height in excess of the radius of the conduit or'tubing, or which but approximate the diameter of the latter; very little and quite insufficient extent orarea of lateral support-is-provided for that part or-extent of a conduit or tubing which lies rearwardly of the fulcrum of applied bending stress, since the greater part of said extent lies wholly outside the bending groove. Since the side walls I l of the bending groove of the tool of this invention are of a height throughout the length thereof which is greatly in excess of the diameter of the conduit or tubing, even as the fulcrum of bending stress shifts rearwardly along the bottom of the bending groove, as the bending operation progresses, a substantial extent of the conduit or tubing rearwardly of the shifting fulcrum continues to be laterally embraced by said side walls, and consequently a highly efficient control of the conduit or tubing and guarding thereof against distortion is provided for throughout the entire bending operation, and until a desired complete elbow bend is attained.

By reference to Figs. 2 and 3 it will also be noted that the cross-sectional shape of the bending groove of the tool of this invention is such as to provide expansion spaces 23 along the junctures of the side walls 14 with the groove bottom l3. These expansion spaces 23 are eccentric to the circular cross section of the conduit or tubing 15, and lie between the central gripping point provided by the groove bottom 13 and lateral gripping points provided by the side walls 14. Such expansion spaces provide breathing room for the stressed metallic walls of the conduit or tubing which undergoes the bending operation, whereby to permit some elastic movement or play thereof so as to facilitate such readjustment of the molecular structure of the metal subject to applied bending stress as may be necessary.

Having now described my invention, I claim: 1. A hand bender of the one sweep type operable upon thin wall metallic conduit comprising an arcuate body having means for attaching thereto a lever arm in radial extension therefrom, said body being provided along its outer periphery with a curved bending groove of a radius corresponding to that of a bend to be produced and approximating 90 in length, said body having outwardly projecting parallel side walls bounding the sides of the bending groove and spaced apart to determine a width of bending groove corresponding to the diameter of conduit to be bent, said side walls being of height, measured from the floor of the bending groove, which approximates one and one-half to twice the dianieter of the conduit to be bent, one of said side Walls terminating in a forwardlyextending' carryingarm providedat'l its endwith a' transverse abutment post spaced outwardly fromthe for ward end'ofthe'bending groove so as to provide an entrance way of awidth approximatingthe diameterof conduit to be bent" through which said conduit can be passed for extension between the-abutment post and the forward end of the bendinggroove, said forward end of thebending groove providing aninitial bending fulcrum engageable by the conduit to be bent; said abutmentpost havinga conduit receiving notch aligned with-the bending groove of said body, the transverse seat of said notch being inclined todiverge from-its outer end-toward its inner end at an acuteanglefrom' theaxisof I an unbent' conduit when the latter isinitially engaged by the tool, the outerend-of said seat providing a long bite impingement shoulder outwardly spaced" at'a maximumdistance from the initial bending fulcrum, and the inner end of said seat=providing a short bite impingement shoulder outwardlyspaced at a minimum distance from the initial bending fulcrum; said inclination of -the-transverse seat of said notch providing clearance between the conduit and the short bite impingement shoulder when the conduit is initially engaged by the long bite impingement shoulder, whereby to permit controlled arching of the conduit and working of the conduit metal at the moment of applied initial bending stress.

2. A hand conduit bender of the kind described comprising an arcuate body having an endwise open curved bending groove extending along its outer periphery, the forward end of said groove providing a shoulder constituting the fulcrum of initially applied conduit bending stress, said bending groove having a curvature length approximating 90 described on a radius corresponding to that of a bend to be produced, said body having outwardly projecting parallel side walls bounding the sides of the bending groove and spaced apart at distance corresponding to the diameter of conduit to be bent, said side walls at their forward ends and for a substantial length thereof extending rearwardly from said ends being of a height, measured from the bottom of the bending groove, which approximates one and one-half to twice the diameter of conduit to be bent, a carrying arm extending forwardly from said body in the plane of one of said side walls, and a transverse abutment post carried by said carrying arm and spaced outwardly from fulcrum shoulder which terminates the forward end of the bending groove so as to provide an entrance way of a Width approximating the diameter of conduit to be bent through which said conduit can be passed for extension between the abutment post and said fulcrum shoulder.

3. A hand conduit bender of the kind described comprising an arcuate body having an endwise open curved bending groove extending along its outer periphery, the forward end of said groove providing a shoulder constituting the fulcrum of initially applied conduit bending stress, said bending groove having a curvature length approximating described on a radius corresponding to that of a bend to be produced; said body having outwardly projecting parallel side walls bounding the sides of the bending groove and spaced apart at distance corresponding to the diameter of conduit to be bent, said side walls at their forward ends and for a substantial length thereof extending rearwardly from said ends being or a height, measured from the bottom of the bending groove, which approximates one and one-half to twice the diameter of conduit to be bent, a carrying arm extending forwardly from said body in the plane of one of said side walls, a transverse abutment post carried by said carrying arm and spaced outwardly from the fulcrum shoulder which terminates the forward end of the bending groove so as to provide an entrance way of a width approximating the diameter of conduit to be bent through which said conduit can be passed for extension between the abutment post and said fulcrum shoulder, said abutment post having a conduit receiving notch aligned with the bending groove of said body, the transverse seat of said notch being inclined to diverge from its outer end toward its inner end at an acute angle from the axis of an unbent conduit when the latter is initially engaged by the tool, the outer end of said seat providing a long bite impingement shoulder outwardly spaced at a maximum distance from the initial bending fulcrum, and the inner end of said seat providing a short bite impingement shoulder outwardly spaced at a minimum dis tance from the initial bending fulcrum, said inclination of the transverse seat of said notch providing clearance between the conduit and the short bite impingement shoulder when the con- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,627,034 Henderson May 3, 1927 1,659,026 Henderson Feb. 14, 1928 1,699,952 Church Jan. 22, 1929 1,752,220 Allen Mar. 25, 1930 2,381,064 Lewin Aug. 7, 1945 

